Comparison of influencess of pathfile and manual file in reduce of instrument fractyre in the protaper rotary system

The new Path File rotary instruments for mechanical pre flaring were recently introduced and it has been claimed to possess numerous merits in the canal preparations. The present study compared the fracture rates during mechanical pre flaring by using manual [k-files] and Path File in the Pro Taper rotary system. This experimental in vitro study was done on 100 acrylic blocks with the similar curve and working length. The root canals were randomly received mechanical pre flaring using Path File and manual k-files in the blocks. The number of the fractured files was determined when SI, S2, Fl, F2 and F3 files would maintained the working length during the repeated uses. The results of both groups were compared by Kaplan-Meier [Log Rank] statistical test. In the manual system, no case of fractures was seen in SI, S2 and Fl files, however, 2 files fractured after 7[th] use in F2 and 3 files fractured after 5th use in the F3 files. No Path file was fractured in SI too. But, in S2, 1 file was fractured after 6th uses, 2 files fractured in Fl after 6th uses, 2 files fractured in F2 after 7th uses and 4 files fractured in F3 after 5th uses. No significant differences were observed between two systems regarding the number of fractured files [p>0.14]. According to the results, Path File rotary system does not show better results during mechanical pre flaring when compared to manual instruments, although no significant differences were noted between two systems

Comparative evaluation of bacterial microleakage of three root canal filling materials, Resilon, gutta flow and Gutta-Percha with AH26 sealer

Apical leakage of tissue fluids around root canal space was cited as the most common cause of root canal treatment failures, for which, fillings of root canal with root filling materials was suggested to achieve adequate apical seal and to prevent leakage. Due to the importance of adequate apical seal, different root canal filling materials were developed and used for this purpose. The purpose of this study was to compare bacterial apical leakage through root canal filling materials of Resilon, GuttaFlow and Gutta-Percha with AH26 sealer. In this in vitro experimental study, 55 single-rooted teeth with healthy roots meeting the study inclusion criteria were selected and randomly divided in 3 experimental groups each containing 15 specimens and 2 positive and negative control groups each with 5 samples. The teeth crown were sectioned near the CEJ, the teeth canals were instrumented with step- back technique while group 1 was obturated with Gutta-Percha, and group 2 with Resilon using a cold condensation technique. Group 3 was obturated with GuttaFlow as recommended by manufacturer. Two-chamber bacterial methods were used to assess bacterial apical leakage by means of Enterococcus Faecalis bacterium during a 60 days time interval. The data were analyzed by Kaplan-Meier test. In root canals filled with Resilon, the median of the day in which leakage was occurred was 17, in Gutta-Percha specimens it was 18 and in canals filled with GuttaFlow the median was 19. 93.3% of the roots filled with each Resilon or Gutta-Percha showed apical bacterial leakage during 60 days while in canals filled with GuttaFlow, the leakage was observed in 80%. Kaplan-Meier test showed no significant differences comparing the day in which the leakage was occurred or the overall incidence of leakage in three materials. Under the conditions of the present study, three root canal filling materials showed similar rates of apical bacterial leakage as no significant statistical differences were noted among them

effectiveness of Mtwo and step back instrumentation techniques on the elimination of enterococcus faecalis from root canal

The aim of this study was to compare the effect of Mtwo rotary system and step back hand system in reduction of enterococcus faecalis bacteria from the root canals of human extracted teeth. In this study, 62 human extracted teeth were divided into two equal experimental groups with 23 teeth each and one control group two extra control groups with 5 teeth each as negative and positive were chosen for confirmation of the canal reinfection too. All of the samples were prepared by K Flie No 20 and Gates Glidden No 2 and 3 before sterilization. Then the teeth were autoclaved and reinfected with enterococcus faecalis. The experimental groups were instrumented either with Mtwo system or step back system. Bacteriological samples were taken after instrumentation to determine the amount of remaining bacteria. In the group 1, fourteen samples and in the group 2, twelve samples represented complete reduction of bacteria. There was not statistically significant difference between two techniques [p>0.05]. Both Mtwo and step back systems are the same on reduction of the bacteria from root canal system, up to the same apical size

[ effectiveness of Hero [taper 4% and 6%] instrumentation techniques on the elimination of Enterococcus faecalis from root canal]

Due to the deeper penetration of bacteria like Enterococcus faecalis into dentinal tubules in pulp diseases, different tapering in root canal therapies leads in different dentinal removal from root canal wall. Then, root canals with higher tapering will contain lower microbial contents. Furthermore, together with higher prevalence of root fractures in teeth with more tapering, the aim of this study is comparing the effect of different tapering of Hero Rotary files [6% versus 4%] in reduction of Enterococcus faecalis bacteria from the root canal of human extracted teeth. Seventy human extracted teeth were divided in two equal experimental [Hero 4%as group 1and Hero 6% as group 2] [n=27] and the control group [n=6].Two extra control group [positive n=5 and negative n=5] took for confirmation the canal reinfection, too. All of the samples prepared by K file No 20 and Gates Gilden No 2 and 3 before sterilization. Then the teeth were autoclaved and were infected with Enterococcus faecalis. The experimental groups were instrumented either with Hero 4% or with Hero 6% files up to #30. Bacteriological samples were taken after instrumentation to determine the level of remaining bacteria. In the group 1 two samples and in the group 2 six samples represented complete reduction of bacteria. There was not statistically significant different between the two groups. Aggressive preparation with an instrumentation technique removing substantial amounts of dentin [Hero 6%] did not reduce the intracanal bacteria more effectively than a more conservative instrumentation technique [Hero 4%] [P>0.05]

[Relationship between Interleukin 4 and 12 and chronic periapical lesion size]

Chronic dental periapical lesions resulted from chronic inflammatory response to the periapical tissues. Since T-helper [CD4+Y] cells are the prominent cells in these lesions, so the aim of this study was to determine the correlation between the concentration of IL-4 and IL- 12 [most important cytokines for differentiation of T helper 2 and T helper 1 cells, respectively], and the diameter of chronic periapical lesions. Thirty-eight chronic periapical lesions were collected which 18 periapical lesions had diameter of >/= 5 millimeter [case group] and 20 periapical lesions had the diameter <5 millimeter [control group]. Tissue samples were cultured for 72 hours, then ELISA [Enzyme linked immuno-sorbent Assay] was used for determining the concentration of IL-4 and IL- 12 in supernatant fluids. Mann-whitney U and Spearman correlation tests were used to analyze the data. IL-4 and IL- 12 were found in all of samples. There was no significant difference between case and control groups regarding the concentration of IL-4, IL- 12 and IL-4/IL- 12. The only significant correlation was between IL-4 and IL-6 concentration without any regard to the diameter of lesions [P<0.001] [Spearman correlation coefficient=0.593]. It is concluded that in chronic periapical lesions, probably T helper 1 and T helper 2 cells participate in active phases of inflammation and tissue damage equally. This could be resulted from mixed population of bacteria in these lesions

[Comparison of three root canal preparation techniques on debris extrusion from apical foramen]

Periapical reparative process, following root canal therapy [RCT] depends on various factors, including the amount of extruded debris to periapical region. The amount of debris extrusion is a determining factor in periapical reparative process. The aim of this study was to compare the three debris extrusion from apical foramen in root canal preparation techniques; manual step back, rotary balanced force and rotary crown down. A total number of 60 single rooted teeth [incisor and premolar] were chosen non-randomly and were divided into 3 groups according to foramen diameter, root length, root divergence and the tooth type. The root canals were prepared according to standard techniques and debris extrusion was evaluated according to Montgomery method. The weights of debris were recorded by 10[-5] gram precision. The data were analyzed by SPSS software version 13 using one way ANOVA and Post-Hoc tests. Mean debris weight for the step back, balanced force and crown down techniques were 0.39 +/- 0.21, 0.22 +/- 0.09 and 0.26 +/- 0.12 mg respectively. The difference among three groups was statistically significant [P<0.05]. The difference between the two rotary groups was not significant. Debris extrusion in manual step back technique was more than the rotary balance-force and crown down technique